Jet augmented ram air scoop

ABSTRACT

Ram air scoop system, particularly adapted for use in aircraft, wherein cabin air from the interior of the aircraft is fed as a high velocity jet into the scoop and passed through a heat exchanger for the cabin air-conditioning system. This has the effect of improving the aerodynamic efficiency of the scoop by increasing the velocity at the exit of the ram air system in flight, resulting in less drag. While the aircraft is on the ground and air is forced through the scoop by a fan or the like, the cabin air can be at a temperature lower than that of the ambient air, this cooler cabin air acting to increase the efficiency of the heat exchanger.

Uiteu States Pate Runnels et al.

[451 Aug. 14, 1973 JET AUGMENTED RAM AIR SCOOP [75] Inventors: Joe N.Runnels, Bellevue, Wash.;

Svend Strandbygaard, North Glenn, Colo. l [73] Assignee: The BoeingCompany, Seattle, Wash.

22 Filed: June 30, 1971 [21] Appl. No.: 158,282

[52] US. Cl 244/118 R, 244/53 B .[51] Int. Cl B64d 13/06 [58] Field ofSearch 244/118 R, 118 P, 244/59, 53 B; 62/D1G. 5, 402; 98/1, 1.5; 165/15[56] References Cited UNITED STATES PATENTS 2,327,737 8/1943 Rendergast244/118 P 2,721,715 10/1955 Hoadley 244/53 B 2,869,535 l/l 9-5.9Horrell;... 244/118 P 3,446,223 5/1969 Hancoc'k.. 244/53'B 2,898,7458/1959 Weisel 98/l.5 X

M CAB/N [0 All? 3,097,504 7/1963 Quick et a]. 62/402 X 3,265,331 8/1966Milesn"; 244/53 B 3,630,138 12/1971 Marcussen et al 98/l.5

. Primary ExaminerMilton Buchler Assistant Examiner- Barry L.Kelrnachter AttorneyBrown', Murray, Flick & Peckham the velocity at theexit of the ram air system in flight,

resulting in less drag. While the aircraft is on the ground and air isforced through the scoop by a fan or the like, the cabin air can be at atemperature lower than that of the ambient air, this cooler cabin airacting to increase the efficiency of theheat exchanger.

7 Claim, 2 Drawing Figures FREE STREAM 1 JET AUGMENTED RAM AIR. SCOOPBACKGROUND OF THE INVENTION Airplane cabin pressurizing systems havebeen devised. which operate. on the principle of drawing hot compressedair from the aircraft engine, reducing. the pressure andtemperature ofthis compressed air to val.- ues suitable forhuman. comfort, and passingthe conditionedair through the pressurized cabin at an ample; I

ventilating rate. Such systems are advantageous in their utilization ofthe. existing air compressor which com-- prises an essential part ofthe. engine. However, the hot bleedair fromathe. engine is at a.temperature of approx imately 400"F. Consequently, this hot air isinitiallypassed through a. heat, exchanger disposed within a ram ducthaving an entrancezscoopand.an'exit nozzlewhich. are usually flush'withthe aircraft skin. Ram airentering the scoop. passes. through the heatexchanger and." is:

then. exhausted: through the exit nozzle, in whichpro cess hot bleed airfrom the engine-passingv through the heat exchanger-is cooled andthereafter passed. to further heat exchangers in the. aircraftair-conditioningsystem. In most conventional systems of this type, the.

cabin air after" it circulates within the cabin, is discharged directlyoverboard. through cabin pressure; 'control valves. 1

SUMMARY OF THE: INVENTION.

In accordanceLwith the present invention, theaerodynamic efficiency of aram' air scoop of; the. type de scribed: above. is improved, resultinginless drag; on the. .aircraft. This; is achi"eved by discharging cabin:air

(which is at a higher pressure than theambientairduring flight)into-the, ram air-scoop as a-high velocity. jet.

Preferably, theairis discharged'intothe ram air'scoop as a high velocityjet which travels along a wall; or: boundary of'the' scoop to. achieve:boundaryv layer con.-

trol; action, giving higher exit plane velocities and therefore,lessdrag; In addition-,the. required. quantity of ambient ram air' isreduced because of the use: of"

cabin air. This means that the duct systemcan bedesigned to reducethequantity of ambientair taken; in with a resultingv lower drag effect.

While theaircraft is on the ground and thecabin is unpressurized', apowered fan, which isusually located in the ramair duct, draws. ambientair through the:

scoop inlet to; cool pressurized air passing through the aforesaid heatexchanger; Discharging cabin air-into the ram duct-during theseconditions increasesthe efficiency of the heat exchanger, particularlyduringv hot weather conditions. That is, during. hot day ground cooling,th'e.ambient1airtemperaturemay be 100 or,

higher, while: the cabin air temperature is approx-i mately75 9Fi Theuseofcabin airin theram airsystem, therefore, increases the.air-conditioning; cooling capa? bilityon. the ground.

' FIG. 2. is across-sectional view of' another. embodiacross the widthofa. scoop. are utilized to improve the aerodynamic efficiency. of the ramair scoop system.

Withreference-now to the drawings, and particularly to FIG. l, the.reference numeral l0..indicates the wall or boundary of a pressurizedaircraft cabin whilethe reference numeral 12 represents the outer skinof the aircraft. Disposed between the cabin wall l0 .and the aircraftskin 12. is a ram air duct 14: having. an inlet scoop 16. flush with theaircraft Sk-IITIZ? and a ram air exit nozzle 18, also flush with the-skin of the aircraft. Theram air duct is preferably located in thewing-body fairing ofthe aircraft; however, other locations on theskinzof the aircraft may be.cused,.depending upon design requirements.

Disposed within the. ram air duct 14. is a heat exchanger, generallyindicated by the reference numeral 20, having an" inlet conduit 22adapted for. connection to asource'ofhotbleed'airfrom the'aircraftenginezand an. exit nozzle 24 adapted for connection to anairconditioning pack,,not shown.

The basic. function of the ram air. scoop system is to provide coolingair for the heat exchanger 20 which reduces-the temperature of thehotbleed air passing into' the exchanger via: conduit 22 from approximately400 F to 250 F prior-to. use in the cabin air-conditioning unit=;.While.the: aircraft isin flight, ramair, indicated schematically by the: arrow26,. enters the intakescoop 16' andflows through the heat exchanger. 20-to theexit nozzle: 1.8.whereit. is discharged. The quantity of intakeair: can. be: controlled by adjusting thearea: of the exit nozzle E8 bya. mechanism, not shown, responsive to the. air-conditioning pack.controls. At the same time,

the:shapee of theinlet end of theram air duct 14 is changeditomaintainflbw stability inthe'scoop. In this respect,v it willJbe noted that theupper wall of the 2 scoop, at the; forward end of the duct 14,.is-formed mentgo'f" the. invention wherein jet nozzles disposedfrom:threeportionst28,30-and.32,,the portion 30 being hingedat itsoppositeends 34 and-36g-to the portions 28 and 32.v The. oppositeend ofportion' 28-,1in turn,.slides on the innersurfaceof the. aircraft skin.12; while the undersurface of the portion 32' slides onthe undersur faceof the top of themainportion of the duct 14. Suit: able mechanicalmeans, not shown, may beutilized to movethe portion. 30" upwardly ordownwardly to thereby vary the. inlet area of the ram air scoop 16 tothe duct 14, in which. process the portion 30' pivots about the hingesati34 and 36.

Disposed within the. duct 14. is a fan aswhich is uti: lizedwhile: theaircraft is onthegroundto force ambient air through: theheatexchanger-Z'O. While: the aircraft is in flightyhowever, the fan 38;is not used,,and ramairflows into the duct 14..

Aswasexpl'ained. above, it.is--necessary,.in a pressurizedi aircraft:cabin, to: discharge pressurized airoverboard in order" to maintain the.circulation of air through the cabin. In accordance with. thev presentinvention, this pressurized cabin air. is utilizedto improvetheaerodynamic characteristics of the: ram air scoop.

exit plane; and, therefore, less net drag is created by the system. Atthe same time, improved aerodynamic efficiency is achieved by virtue ofthe boundary layer control action to give higher exit plane velocitiesand less drag. A further drag reduction is achieved by using cabin airas part of the required heat sink. That is, the quantity of outside air(i.e., ram air) is reduced.

During ground operation when the cabin is unpressurized, the powered fan38 located within the ram air duct draws ambient air through the scoopinlet 16 and cabin air through the nozzle 48 to cool the pressurized airpassing through the heat exchanger 20. During hot day ground cooling,the ambient air temperature may be as high as approximately 100 F whilethe cabin air temperature is approximately 75 F. Thus, the use of cabin.air in the ram air circuit increases the airconditioning coolingcapability on the ground since the air passing through the heatexchanger during these conditions is cooler than it otherwise would be.

In FIG. 2, another embodiment of the invention is shown which is similarto that of FIG. 1 except that in this case the cabin air enters the duct14 through a plurality of nozzles 50 more or less centrally locatedwithin the duct. This has the effect of increasing the pressure at theduct exit plane, but does not necessarily improve boundary layerconditions.

Although the invention has been shown in connection with certainspecific embodiments, it will be readily apparent tothose skilled in theart that various changes in form and arrangement'of parts may be made tosuit requirements without departing from the spirit and scope of theinvention.

We claim:

l. A ram air scoop system for an aircraft having a pressurized cabincomprising a ram air-duct having an inlet opening through which ram airenters the duct and an exit nozzle through which ram air leaves theduct, heat exchanger means disposed within the duct, conduit meansconnecting the interior of the pressurized cabin with the duct andnozzle means opening into the duct connected with the conduit means forinjecting cabin air into the duct to thereby improve aerodynamicefficiency of the ram air scoop system and reduce the drag on saidaircraft due to said ram air scoop system.

2. The system of claim 1 wherein said nozzle means is disposed withinsaid duct to create an air jet adjacent a wall of the duct, therebyimproving its boundary layer conditions.

3. The system of claim 1 including a plenum chamber interposed betweensaid nozzle means and the conduit means connecting the interior ofsaidpressurized cabin, with the duct, and valve means in said conduitmeans.

4. The system of claim 1 wherein said nozzle means is disposedessentially centrally within said ram air duct.

5. The ram air scoop system of claim 1 including in an inner wall of thescoop at its inlet opening three movable wall portions two of which areouter portions and the third of which is a center portion intermediatethe outer portions and means hinging each outer portion to its adjacentend of the center portion, the end of one outer portion opposite thecenter portion being adapted to slide along the inner surface of theaircraft skin and the end of the other outer portion being slidablealong the underface of the top of the ram air duct so that movement ofthe center panel toward or away from the aircraft skin varies the inletarea of the ram air scoop.

6. The ram air scoop system of claim 5 in which the nozzle means arepositioned adjacent to the hinging means between the center moveablewall portion and the outer portion sliding on theunderface of the top ofthe ram air duct.

7. The ram air scoop system of claim 5 including a plenum chamberconnected between the conduit means and the nozzle means, the plenumchamber beingpositioned adjacent to the hinging means between the centermoveable wall portion and the outer portion sliding on the underface ofthe top of the ram air duct.

1. A ram air scoop system for an aircraft having a pressurized cabincomprising a ram air duct having an inlet opening through which ram airenters the duct and an exit nozzle through which ram air leaves theduct, heat exchanger means disposed within the duct, conduit meansconnecting the interior of the pressurized cabin with the duct andnozzle means opening into the duct connected with the conduit means forinjecting cabin air into the duct to thereby improve aerodynamicefficiency of the ram air scoop system and reduce the drag on saidaircraft due to said ram air scoop system.
 2. The system of claim 1wherein said nozzle means is disposed within said duct to create an airjet adjacent a wall of the duct, thereby improving its boundary layerconditions.
 3. The system of claim 1 including a plenum chamberinterposed between said nozzle means and the conduit means connectingthe interior of said pressurized cabin, with the duct, and valve meansin said conduit means.
 4. The system of claim 1 wherein said nozzlemeans is disposed essentially centrally within said ram air duct.
 5. Theram air scoop system of claim 1 including in an inner wall of the scoopat its inlet opening three movable wall portions two of which are outerportions and the third of which is a center portion intermediate theouter portions and means hinging each outer portion to its adjacent endof the center portion, the end of one outer portion opposite the centerportion being adapted to slide along the inner surface of the aircraftskin and the end of the other outer portion being slidable along theunderface of the top of the ram air duct so that movement of the centerpanel toward or away from the aircraft skin varies the inlet area of theram air scoop.
 6. The ram air scoop system of claim 5 in which thenozzle means are positioned adjacent to the hinging means between thecenter moveable wall portion and the outer portion sliding on theunderface of the top of the ram air duct.
 7. The ram air scoop system ofclaim 5 including a plenum chamber connected between the conduit meansand the nozzle means, the plenum chamber being positioned adjacent tothe hinging means between the center moveable wall portion and the outerportion sliding on the underface of the top of the ram air duct.